This invention relates to a multicylinder reciprocal engine having an integral positive displacement, rotosupercharger for boosting compression in the pressures cylinder chambers for improved performance. The engine of this design relates to the invention titled REGENERATIVE THERMAL ENGINE, filed Dec. 5, 1985 , U.S. Pat. No. 4,791,787, issued Dec. 20, 1988. In the referenced patent application, the invention related to a single cylinder engine having positive displacement rotosupercharging with auxiliary turbocharged arrangements for developing the maximum power and efficiency possible for a single cylinder engine.
When coupling a positive displacement rotosupercharger to a reciprocal piston engine, provision must be made to prevent pressure loss between the coupled positively displaced rotosupercharger and the reciprocal cylinder engine. The particular advantage of a single cylinder engine is that the rotosupercharger can be directly coupled to the reciprocal engine and the cycle of the rotosupercharger components matched to the cycle of the reciprocator component with minimal dead space. In this manner the substantial compression achieved by the positive displacement rotosupercharger can be directly supplied to the reciprocator with minimal pressure and kinetic loss. The single cylinder embodiment, whether with one piston or two opposed pistons, is a unique arrangement.
When a positive displacement rotosupercharger is coupled to a multi-cylinder engine, however, the situation is substantially different. Such arrangement on the compression side requires an intermediate valve to sequentially connect each of the positively displaced rotosuperchargers to the operative cylinder only at the time it is ready to deliver peak pressure developed in the compression cycle. Compressed air must be prevented from reentering the supercharger at the beginning of compression cycle. Where the connection path is short as in single cylinder systems, an open system results in small losses, the volume of the passage being added to the minimum displacement volume of the positive displacement compressor in calculating compression ratio.
Similarly, when the rotosupercharger utilizes the exhaust gases from the reciprocator the situation for a single cylinder reciprocator coupled to a positive displacement expander is substantially different than when a multiple cylinder reciprocator is integrally coupled to a single positive displacement expander. Again, in order to utilize the peak pressures developed in the reciprocator fully by the expander a distributor means must be interposed between the multicylinder reciprocator component and the positive displacement expander component.
In a prior art device of Kemp, German Pat. No. 3,000,145 issued July 1981, a multicylinder reciprocator engine is shown connected to a rotosupercharger having a positive displacement compressor and a positive displacement expander. Both the intake and exhaust of the multicylinder of the reciprocator are connected to an intermediate manifold that connects to a entire bank of cylinders. The use of a common manifold creates a large dead space into which the peak exhaust is sequentially dissipated without producing useful work. The high potential and kinetic energy of the expanded cylinder gases which are limited in volume, first expand into the exhaust manifold servicing all four cylinders, then, if any energy remains, expand into the supercharger expander. The common exhaust manifold is an effective sink rather than a directional path for reciprocator exhaust.
In a similar manner the peak pressure of the compressor side of the rotosupercharger in the Kemp system is not selectively directed into an individual cylinder of the reciprocator, but is diluted by the common intake manifold. Additionally, since the outlet passage of the rotary compressor in Kemp is exposed over a substantial duration of the rotary cycle, gases compressed by the previous cycle will backflow into the compressor chamber of the compressor portion of the rotosupercharger. The effective volume of the compressor then becomes a maximum volume of the positive displacement compressor plus the volume of the manifold and its accompanying service passages. The compressor rating then falls dramatically.
Such inefficiencies are multiplied by the number of cylinders serviced and the number of spaces in the rotor. The more cylinders, the more inefficient the rotorsupercharger becomes.
In addition to these inefficiencies in prior art devices, additional problems are encountered when utilizing a compound rotary-reciprocal engine. Since the preferred means of positive displacement supercharging is the Wankel-type configurations, means must be devised to compensate for the disparity in required volume between the compressor side and the expansion side when a common rotor is utilized to both compress and expand gases in conjunction with the demands and products of a reciprocal component. These various problems are solved by the arrangements described in this specification.